/**
 * 97.交错字符串
 */
public class Exerciser6 {
    public boolean isInterleave(String s1, String s2, String s3) {
        int m = s1.length();
        int n = s2.length();
        if(m + n != s3.length()) {
            return false;
        }
        s1 = " " + s1;
        s2 = " " + s2;
        s3 = " " + s3;
        boolean[][] dp = new boolean[m + 1][n + 1];
        // 初始化
        dp[0][0] = true;
        for(int i = 1;i <= m;i++) {
            if(s1.charAt(i) == s3.charAt(i)) {
                dp[i][0] = true;
            }else {
                break;
            }
        }
        for(int j = 1;j <= n;j++) {
            if(s2.charAt(j) == s3.charAt(j)) {
                dp[0][j] = true;
            }else {
                break;
            }
        }

        // 填表
        for(int i = 1;i <= m;i++) {
            for(int j = 1;j <= n;j++) {
                if(s1.charAt(i) == s3.charAt(i + j) && dp[i - 1][j]) {
                    dp[i][j] = true;
                }else if(s2.charAt(j) == s3.charAt(i + j) && dp[i][j - 1]) {
                    dp[i][j] = true;
                }
            }
        }
        return dp[m][n];
    }
}
